Starter Question

Joe KCMO

Joe KCMO

Senior Member
I have a starter that when hooked up to a 6V battery charger/starter spins slowly then trips the circuit breaker in the charger/starter. Is it a bad connection with the clips or possibly a short in the starter. Opinions/advice.
 
Is there a way (amount of resistance)and how to measure the resistance of the armature and field coils to confirm?
 
Also check the condition of the bushings; I've read where loose bushings can allow the armature to rub on the fields if they are bad enough, possibly producing the symptoms you describe.
 
Here is diagram of a Ford starter.

Flathead_starter_1938-48.jpg
 
If you look at the back cover (11049) two of the bridges that house the brushes are riveted to the back cover with insulation washers; two do not have the insulated washers. The two without, should hold the brushes that are grounded to the case.
Been there done this one before. The starter will slowly turn, then any breaker will blow.
Sound familiar?
 
You also need 11036 fibre thrust washer. 11140 is a bracket, starter to oil pan, although not part of the problem, you should have it. Good luck on your starter problems, let us know what you find.
 
It's probably the charger, there are not many chargers that can put out the 150-200 +amps to spin the starter on the bench---without a battery to help, retry your testing with a good battery.

The fact that it is tripping the breaker in the charger means that the charger is being overloaded. How many amps is your charger??
 
Boy! Thats not how to test a starter motor. A starter draws approx 50 plus amps if spinning not under load (not cranking the engine) and 200 plus amps under load cranking an engine. I bet your 6 volt charger is only capable of 3 to 6 amps. This is why the charger circuit breaker is tripping out. Never use a charger as a source of power for testing ANYTHING! To test the starter connect it to a fully charged battery and dont make the last connection at the battery as a spark here may blow up the battery. Better still take the starter to an auto electrical shop and have them test it under load in their test bench. Regards, Kevin. (Retired auto electrician).
 
My charger has a starter mode of 125 amps in 6 volt. I would think enough to spin a starter not under load.

I think I have found the problem. The two brush holders which are insulated and hold the field coil brushes should not make contact with the case. A volt/ohm meter revealed that there was conductivity of the two field coil brush holders to the case. Can these be rebuilt. Need new rivets (11069)and insulators(11068 & 11062). Or are "good" front plates available. I would like to save a good starter for only a few bucks in parts. I also like the challenge of fixing things without just buying new. Any help in finding the insulators and rivets to hold on the brush holders?
 
You might find a end plate on e-bay or maybe joblot. I don't think the small parts are available. find a old starter for parts. or maybe a Forbarner will have what you need, or a better idea than mine.
 
Hi Again, as I said before you should never use a battery charger as a power supply for testing anything unless of course it is actually connected up to a battery and then it is OK as you will then have a stable voltage and enough current (amps) will be available for testing. Your starter end housing insulated brush holders can be tested with an ohm meter so long as it is disconnected from the brushes and field coils. Probually better to test the insulated brush holders by using the battery and two small test leads from the battery terminals to end housing body and brush holders and see if there is a small spark or leakage at the insulators. Use a 12 volt battery here which is double the normal operating voltage of the cars system. Ohm meters can be a bit over sensitive in some automotive testing applications, especially if fibre insulators are soaked in oil or dirt or solvents. Make sure parts are clean and dry before testing. Regards, Kevin.
 
Koates makes a good point regarding testing the end plate. You cannot have the brushes in place. If you do you will get continuity thru the coils giving a false indication. I have never seen an end plate that was faulty. If you think yours is, remove it completely from the starter, then check on a mid range ohms scale. I concur also, use a good battery, not a charger for testing. If you had the correct brushes in the correct holders, and your starter is still very week, your problem is elsewhere.
 
I did have the end plate removed. One brush holder read infinite resistance, the other was between a couple of thousand to megohm. I will try using voltage instead of ohm's tonight.

What effect does the armature and field coils have on performance(poor) of a starter?
 
You have 4 brushes in a starter. Like kind opposing each other. 2 grounded, 2 not.
The armature and field coils operate on opposing magnetic fields. The armature is constantly finding itself propelled by an opposite magnetic field, from which it never escapes as long as current flows. Consequently, the quality of the commutator to brush contacts determines the torque of the starter.

Is this a starter you rebuilt? Had rebuilt? From your car? or one your just playing with?
 
This starter is one that I bought with condition unknown(not new or rebuilt). I think that I might finally have the answere (again). After washing with alcohol and removing all the paint from the rivets which should not be grounded and letting sit overnight, the conductance is 0 for the two field coild brush holders.

What I did notice, thankyou jdl, was that the thrust washer was missing and allowing the brush holders to touch the armature base. I need a thrust washer. Any suggestions on where to get one or how to make. I am having a good time solving this puzzle. The reward, a backup starter that I thought originally I got burned on. Thank you Fordbarn.
 
I used a homemade leather washer in my starter when i rebuilt it ---40 years ago, it is still working, it works good enough that i have been accused of having a 12v battery.
It came from an old work boot.
 
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